The invention relates generally to the surface treatment of workpieces.
More particularly, the invention relates to an apparatus for continuously advancing workpieces through a surface treatment zone while simultaneously rotating or tumbling the workpieces.
An apparatus of this type is described, for example, in the aforementioned U.S. Pat. No. 4,757,647. This apparatus has a cage-like receptacle for the workpieces and the receptacle is mounted for rotation on an at least approximately horizontal axis. The receptacle comprises a tubular shell or sheath made up of a multiplicity of circumferentially spaced, elongated components such as rods or wires which extend in parallelism with the rotational axis of the receptacle. The arrangement is such that, when the receptacle rotates, the elongated components move lengthwise as they travel upwards from the lowest point of the rotational path of the receptacle. This lengthwise movement of the components is in the intended direction of advance of the workpieces.
The known apparatus has the drawback that it cannot be used for the transport of flat, plate-like workpieces or heavy workpieces.